Some Kind of Caliper, But for What?

Can't really see the shape of the contact points - could you you post a close-up of that end?

Arrrgghh, it's out of my possession. I should have thought to do that.

Anyway, the points had a fairly thin rubberized coating. They were not bare metal.

Hooker

OK. Were the contacts pointed or flattened? What resolution and units are on the dial?

IIRC, the points were necked down to a very small (less that about 1/32") flat area. Dial was in inches and .001" resolution.

Hooker

Hi Hooker,

OK, since it measures in mils, the tolerance does seem about right for sheet metal as JustAnEngineer has said or some other fairly thin material emerging from some sort of flattening/extrusion process.

At first I thought it would be wood; plywood or particle board. Standard US widths are 48". This caliper is long enough to reach the middle of the pieces, but I think that ±1 mil is not right for wood since you have a surface topology (peaks and valleys) that is somewhere in the neighborhood of ±20 mils.

My best guess is testing for uniform thickness of relatively hard, smooth-surfaced materials in widths under 48", and thicknesses between 0.020 and 0.200 inches. Could be plastics or metals; maybe even glass.

Mike

very close, but it is that long to not have to go to the other side of the sheet.

Very good. I thought about that too. That's why I said "widths under 48 inches". I can see operators not wanting to cross over from one side to the other, just to take measurements. So, can we agree on widths LTE 24"?

GA - better than the 8

Thank to the soft I loaded here is a magnified view of the ends.

The rubber can be seen.

I must say I like the handle on it!

It is obvious close for many but you give a complete field of use. It is more than for one purpose. We had it in the paper processing plant to inspect coating thickness on a machine with coils. Good Answer

Don't know what it's intended purpose was but my father left me one similar to it when he passed away. He used to use it to measure the thickness of anything that was wider than what his regular calipers and micrometers could reach such as wood, sheet metal, steel plate, plate glass, etc. I haven't found any other uses for it other as a conversation piece in my accumulation of wierd and unknown function tools collection

Hi old salt,

I haven't found any other uses for it other as a conversation piece in my accumulation of wierd and unknown function tools collection.

Maybe you could post some pictures of said tools. I'm sure many of us would like to see them!

Mike

Seems to me I saw one of those used in the tannery that Mike Roe was in when he did a "Dirty Jobs" episode.

I like the idea that it might be a QA tester...there are a lot of tools used in QA which are not found anywhere else. (We used to joke about the guy legendary guy who sent back three box cars full of railway wheels only to find out that his hammer had a crack in it! I know...its a QA joke...we were always a non-humourous bunch.)

But other than that, I'm guessin'

I have seen and used similar tools quite often. They are used for measuring wall thickness of pipes, plates, furnace tubes, impeller vanes etc. where you need to measure away from the edge.

The reason for the long "thin" design is so that it fits into a pipe to measure wall thickness. Small anvils are usually curved to measure "round" surfaces.

Not sure if they have a specific name, I have always called them Thickness Calipers for pipe wall measurement.

A picture of thickness caliper (or groove caliper) though this one is not useful for pipe wall thickness measurement.

External Caliper Gauge

Features Manufactured in Germany One fixed and one moving arm with adjustable carbide spherical contact points. The deflection of the moving contact point is transmitted to the clear dial indicator, the results can be read directly. For quick measuring of external grooves, wall thicknesses, plates,pipe wall thickness, foils etc. Supplied with test certificates

similar, but your tips are sharper, more sexy

Another term which might be of help is "Snap Gauge" - sometimes, knowing the tool's name can be a real help! But it may have six names in five industries.... See http://dijite.hisupplier.com/product-190079-Digital-Outside-Snap-Gauge.html for example or http://www.tengtools.com.au/external-snap-gauge.html. Typically, these are set to the material's nominal thickness (often by rotating the dial so that it reads zero at that thickness), and the inspector can make a quick check; any deviation from zero tells direction and amount away from nominal; if the dial has a pair of movable tabs set, it will show whether the reading is in or out of tolerance. Digital ones have similar capabilities, and may add datalogging ports.

The second instrument above may be for reading wall thickness in tubing or pipe, hence one straight jaw to go down minimum bore, but other one can clear flange, fitting, etc. Here's another: http://www.saifuddin-co.com/gauges.htm. All of these have a means to operate the device with one hand, opening the jaws and permitting them to close upon the item to be checked.

I've been keeping up with this thread. Would anyone like to actually read my post - #8?

Why? What you are getting now is posts from people who have actually used the tool. Are your feelings so easily hurt?

No - it's not that, I just put a lot of thought into it and got almost no feedback. By the way, I have voted for GAs for several contributors here. I believe that you can have merit for knowing something through experience. But, to be able to zero in on something using scientific principles and deduction is even more important. Who knows or has experienced everything? Both have the potential to be worthy of GAs.

I suspect the manufacturer is the Federal Mogul Bearing company. I have used similar caliper from Starrett in turbojet engines 'hotends' with carbon multi split oil seals. The turbine shaft with a seal spigot is deep in a cylindrical housing which cannot be accessed without a complete strip of the engine. The tong tips were covered with a very hard teflon coating so as not the score the sealing surface which the carbon seal runs on when testing for wear limits.

This may help.

Since it has rubber coated measuring contacts, I would think that it is used for checking molds used in injection/compression molding. The coated tips would be to protect the molding surface for the smallest scratch will reflect in one's molded part. This would be quite usefull for checking tolerances and wear on a wide and flat mold without having to completly disassemble it.

Does it open wider than it's maximum measurement thickness?

What about double glazing units?

Depending on the hardness of the rubberized coating on the tips, it could be used for anything from measuring the thickness for paper products to other scratch sensitive material for which metal contact may not be advisable. Regardless of the material for which it is intended, it is obvious that the concern is for measuring away from the edge: perhaps a groove or a rise in the shape of the product, or simply checking uniformity of parallel surfaces. However, as the smallest increment is 0.001", it seems prudent to suppose that the tolerance that may be in the area of + or - 0.010" (per standard QC methodology). Given that there are only two points of contact for the tool, I would not use it for anything requiring greater accuracy.

Is the rubber tip removable, protecting a metal point?

I got to take another closer look at the caliper. The tips are actually not rubberized as I originally thought, but are blackened steel with a dome shape on the working end. The tips were also knurled for, I assume, toolless removal but most of the knurling is worn off.

Thanks for all your responses. I'm overwhelmed, but suppose I really shouldn't be, given the audience.

Hooker

PS - the people who provided the tool are monitoring this thread and are impressed with the response!!

OK - I vote for GAs all around!